Liquid crystal alignment on inkjet printed and air-buffed polyimide with nano-grove surface

Hwang, Jeoung‐Yeon; Chien, Liang–Chy

doi:10.1088/0022-3727/42/5/055305

Cited by 9 publications

(6 citation statements)

References 19 publications

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“…Further, to verify the relationship between the ability of the LC molecules to maintain their orientation and thermal stability, we used silica nanoparticle and dispersed in LC mixture as well as filled in LBL ITO cell. Dispersions of small nanoparticles in anisotropic fluids were subject of interest for a long time, where surface interactions strongly influence the orientational ordering of LC. Figure shows the photomicrographs of the interaction of LC with silica nanoparticles with a diameter of 12 nm.…”

Section: Resultsmentioning

confidence: 99%

“…Many techniques for anchoring LC molecules on the surface with alignment layers were reported. [3][4][5][6][7][8][9][10][11] However, up to now, the method based on the surface rubbing process has dominated the mainstream of the LCDs development. So, vertical alignment (VA) LCDs with homeotropic polyimide are used in LC cells as an alignment layer by a mechanical rubbing process, which generate micron-sized parallel grooves.…”

Section: Introductionmentioning

confidence: 99%

“…The substrate surface is produced to provide anchors for the LC molecules. Many techniques for anchoring LC molecules on the surface with alignment layers were reported . However, up to now, the method based on the surface rubbing process has dominated the mainstream of the LCDs development.…”

Section: Introductionmentioning

confidence: 99%

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Homeotropic alignment of liquid crystals on ITO surface using LBL assembly

Chandrashekhar

Park

2018

J Soc Info Display

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In this work, the very thin layer‐by‐layer (LBL) film that was constructed by dip coating method on indium tin oxide surface can be used in liquid crystal (LC) displays devices. The obtained results indicate that the ultrathin LBL film shows the homeotropic alignment layer, and a uniform vertical alignment of LC molecules was gained very easily. The progress of vertical‐aligned LC cells with a LBL layer was evaluated. The obtained threshold voltage and response time of the LC cell were 2.472 V and 12.5 ms, respectively. So, the competitive performance of the LC cell could allow new sign at a low‐cost budget with rubbing process in LC display technology.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Homeotropic alignment of liquid crystals on ITO surface using LBL assembly

Chandrashekhar

Park

2018

J Soc Info Display

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“…The photoalignment is a well-known technique for LC alignment via an anisotropic surface interaction capable of a large area uniform alignment for display applications 29 – 31 . At the same time, photoalignment has a unique potential for creation of complex LC orientation patterns implementing lattices of topological features for active control of soft matter LC systems 32 . Until now an azo dye LC photoalignment has only been demonstrated on a non-patterned porous graphene layer for terahertz LC phase shifter 16 .…”

Section: Introductionmentioning

confidence: 99%

Command Electro-Optical Switching of Photoaligned Liquid Crystal on Photopatterned Graphene

Varanytsia

Chien

2017

Sci Rep

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We report command electro-optical switching on photolithographically-patterned graphene into a high-density electrode pattern for a high-transmission in-plane-switching (IPS) liquid crystal device. A highly-effective liquid crystal photoalignment method is used to maximize the field-driven optical contrast of a prototyped device. A non-contact and low-temperature photoalignment allows delicate surface treatment required for successful processing of graphene layer into an IPS electrode structure. Electro-optic performance of the graphene-based single pixel laboratory IPS prototype demonstrates the application potential of graphene for liquid crystal electro-optic devices with complex and high-definition electrode patterns.

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“…Many alignment techniques for inducing anisotropy on the surface of the LC alignment layer have been reported. [1][2][3][4] Generally, polyimide ͑PI͒ is used in LC cells to align them using a mechanical rubbing method. However, the rubbing process damages the alignment film, which limits the yields and stability of LCDs.…”

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confidence: 99%

Plasma-Beam-Processed Polyimide Films for the Alignment of Liquid Crystal Molecules

Ho¹,

Lee²,

Kuo

et al. 2010

Electrochem. Solid-State Lett.

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We demonstrate a plasma-beam-processed polyimide ͑PI͒ surface to effectively align liquid crystal ͑LC͒ molecules. The pretilt angles of LCs can be varied between 0 and 3.5°, and the PI surface energy can be adjusted by controlling the plasma beam with an energy of 450 eV at an incident angle varying from 0 to 80°with respect to the normal direction of the substrate. Additionally, a method was developed to quickly evaluate the level of anchoring force of LC when compared with a rubbed-aligned LC cell. The performance of this method should be under LC cells with the same alignment materials.Controlling liquid crystal ͑LC͒ alignment is one of the most important manufacturing processes in liquid crystal display ͑LCD͒ technology. Many alignment techniques for inducing anisotropy on the surface of the LC alignment layer have been reported. 1-4 Generally, polyimide ͑PI͒ is used in LC cells to align them using a mechanical rubbing method. However, the rubbing process damages the alignment film, which limits the yields and stability of LCDs. Drawbacks of mechanical brushing including generation of dust and electrostatic charges are well-known. The rubbing process also damages bus lines and leads to electrical static discharges on thin film transistors in LCDs. Although the rubbing of the PI layers remains the current method of choice for the production of LCDs, noncontact alignment technologies have attracted much attention in the LCD manufacturing sector. They have great potential for future generations of large, high resolution LCDs. To avoid damage in aligning layers of the LCDs, noncontact alignment methods, such as photo alignment, 5-7 ion beam alignment, SiO 2 alignment, 8-12 and plasma alignment, 13,14 have been proposed for LC alignment. However, the photo alignment method is unreliable, the ion beam alignment method has issues related to uniformity, and SiO 2 oblique deposition system has trouble with large substrates.In this article, a simple LC alignment technique that uses a collimated plasma beam is proposed. The beam is used to treat commercial PI surfaces and then to align LC on a glass substrate. An LC can be homogeneously aligned on commercial PI surfaces using the appropriate incident angle and energy of the plasma beam. The pretilt angle and threshold voltage ͑V t ͒ of the twist nematic ͑TN͒ LCDs can be controlled by adjusting the plasma beam parameters. Moreover, we propose a new method that can quickly evaluate the level of anchoring force of LC by stressing the LC cell at an applied voltage of 10 V for 10 min when the integral area difference of voltage-transmission curves before and after stresses are done. The anchoring force of the Ar-plasma-beam-aligned LC cell at incident angle of 60°is in accordance with that of the mechanical rubbing aligned LC cell. ExperimentalThe alignment layers were composed of PI ͑4170 R2, Nissan Chemical͒, which was printed on 10 ⍀/ᮀ indium tin oxide ͑ITO͒-coated glass substrates ͑50 ϫ 50 mm͒. They were softly baked at 80°C for 10 min to evaporate the solvent within the...

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Liquid crystal alignment on inkjet printed and air-buffed polyimide with nano-grove surface

Cited by 9 publications

References 19 publications

Homeotropic alignment of liquid crystals on ITO surface using LBL assembly

Homeotropic alignment of liquid crystals on ITO surface using LBL assembly

Command Electro-Optical Switching of Photoaligned Liquid Crystal on Photopatterned Graphene

Plasma-Beam-Processed Polyimide Films for the Alignment of Liquid Crystal Molecules

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